Coxiella manipulation of cholesterol in the intracellular niche

项目概要/摘要 贝氏柯克斯体是人类Q热的病原体，Q热是一种人畜共患疾病，可导致虚弱的流感， 比如急性疾病，或者慢性病人的危及生命的心内膜炎。Q热患者出现 很少有明显的临床特征，慢性疾病需要至少18个月的抗生素治疗 治疗，强调需要新的治疗方法。一种专性细胞内病原体，柯克斯体存活 在一个大的，溶酶体样的寄生虫空泡内，这是细菌复制所必需的， 细菌从宿主的免疫反应。寄生考克斯体空泡（CPV）的形成， 与宿主内体和自噬体的异型融合，这是一个也将胆固醇递送到细胞的过程。 CPV膜。我们最近确定，CPV中宿主胆固醇的积累对宿主细胞是有毒的。 假设Coxiella必须消耗CPV胆固醇才能在宿主细胞内存活。 本申请的目的是检验我们的假设，即柯克斯体使用两种不同的机制， 操纵CPV胆固醇。目的1将测试膜接触部位在胆固醇转移之间的作用， CPV和宿主内质网。目的2将确定假定的柯克斯体甾醇的作用 还原酶修饰CPV胆固醇。在这些研究的结论中，我们将阐明如何 Coxiella操纵宿主胆固醇以维持细菌存活的最佳微环境。

PROJECT SUMMARY/ABSTRACT Coxiella burnetii is the causative agent of human Q fever, a zoonotic disease that can cause a debiliting, flu- like illness in acute cases, or a life-threatening endocarditis in chronic patients. Q fever patients present with few distinguishing clinical features, and chronic disease requires a minimum of 18 months of antibiotic treatment, highlighting the need for new therapeutics. An obligate intracellular pathogen, Coxiella survives inside a large, lysosome-like parasitophorous vacuole that is essential for bacterial replication and protects the bacteria from the host immune response. The Coxiella parasitophorous vacuole (CPV) forms through heterotypic fusion with host endosomes and autophagosomes, a process which also delivers cholesterol to the CPV membrane. We recently determined that accumulation of host cholesterol in the CPV is toxic to the bacteria, and hypothesize that Coxiella must deplete CPV cholesterol in order to survive within the host cell. The objective of this application is to test our hypothesis that Coxiella uses two distinct mechanisms to manipulate CPV cholesterol. Aim 1 will test the role of membrane contact sites in cholesterol transfer between the CPV and the host endoplasmic reticulum. Aim 2 will determine the role of putative Coxiella sterol reductases in modifying CPV cholesterol. At the conclusion of these studies, we will have elucidated how Coxiella manipulates host cholesterol to maintain the optimal microenvironment for bacterial surivival.